The invention is generally suited for any application involving cushion pads, and, more particularly, for use in connection with off-the-road vehicles, e.g. large trucks, wherein it is desirable to provide a soft cushioning effect in the suspension systems of the vehicles, when they are operated empty and without loads, and a much firmer or harsher cushioning effect, when the vehicles are operated fully loaded.
U.S. Pat. Nos. 3,086,765 and 3,537,696 are typical of the many patents relating to circular cushion pads which are generally composed of a single rubber ring which has a generally frusto-conically shaped cross-section and is bonded to one or both sides of an annular rigid plate. U.S. Pat. No. 4,025,063 is typical of the many patents relating to rectangular cushion pads which are essentially composed of a plurality of parallel rubber cushions, each of which has a generally frusto-conically shaped cross-section. The invention is directed to an improved composite cushion pad having a different configuration which initially provides soft ride characteristics with improved resistance to compression when placed under a load.
Briefly stated, the invention is in a composite cushion pad which has a rigid plate with opposing planar surfaces. A first, bottom cushion of resilient elastomeric material is bonded to at least one of the opposing surfaces of the plate and extends therefrom. The bottom cushion has a generally frusto-conical cross-section defined by a pair of opposing sidewalls which converge towards each other in a direction away from the plate. At least one other resilient elastomeric top cushion is disposed in superimposed relation atop the bottom cushion and, likewise, has a generally frusto-conical cross-section defined by a pair of opposing sidewalls which also converge towards each other in a direction away from the plate. The converging sidewalls of the top cushion or cushions, adjacent the converging sidewalls of the bottom cushion, are laterally offset from the converging sidewalls of the bottom cushion inwardly towards each other to form a composite cushion of differently sized cushions with a pair of opposing stepped sidewalls.